Influence of gear type on injuries and survival of adult Coho Salmon released from recreational marine fisheries

Objective Catch and release is a common conservation and management tactic that is used in marine Coho Salmon Oncorhynchus kisutch fisheries in British Columbia, Canada. Recent studies have found higher levels of release mortality when Coho Salmon are injured, but the role of specific gears or practices in causing injuries has not been explored for Coho Salmon that are released at sea. Methods We compared fishing injuries for Coho Salmon (n = 226) that were captured by two hook sizes (3/0 or 5/0) and three landing methods (knotless rubber-coated net, knotted polyethylene net, or no net). The captured adult Coho Salmon were then tagged and released with acoustic transmitters and tracked along their return migrations through the Salish Sea using an acoustic receiver network. Results Hook size had no effect on frequency of any hooking injuries (eye injuries and bleeding). The fish that were landed with knotless nets exhibited less scale loss than those that were landed with knotted nets but had a greater number of fins damaged. The fish that were landed without a net had the least scale loss and fin damage but were smaller overall than those that were landed with a net, so size differences may have influenced injury outcomes to some extent. Coho Salmon with less scale loss and larger body size had higher survival to a line of acoustic receivers that were located 50 km away in the Salish Sea. When considering multiple injuries, survival was compromised in fish that were in poor condition relative to those that were in good condition (37.2 vs. 21.4% release mortality, respectively; odds ratio = 2.04, P = 0.044). Conclusions These results indicate that reducing handling and netting (i.e., releasing fish at the waterline) will minimize injuries and improve release survival. We use our results to recommend best practices for capture and release of Coho Salmon at sea.